import java.util.HashSet;
import java.util.Set;

public class Test4 {
    public static void main(String[] args) {
        Set<Student> students = new HashSet<>();

        students.add(new Student("张三","男",20));
        students.add(new Student("李四","女",21));
        students.add(new Student("张三","男",20));

        for (Student student : students) {
            System.out.println(student);
        }
    }
}
